I rolled back to xorg-server-1.16.1-r4. That's what I had before the updates. I had to add the following to my /etc/portage/package.mask file in order to down grade:
>x11-base/xorg-server-1.16.1-r4
=app-admin/eselect-opengl-1.3.1-r3
=x11-proto/glproto-1.4.17-r1
>media-libs/mesa-10.3.5
=x11-drivers/xf86-input-evdev-2.9.2
=x11-drivers/xf86-input-synaptics-1.8.2
>sys-devel/llvm-3.5.1
Then I used
# emerge -C eselect-opengl -a
# FEATURES="-colision-protect" emerge xorg-server -1av
to roll back xorg-server.
Gnome is functioning correctly again. Here's the output of ck-list-sessions:
# ck-list-sessions
Session4:
unix-user = '1000'
realname = 'Joe Derp'
seat = 'Seat1'
session-type = ''
active = TRUE
x11-display = ':0'
x11-display-device = '/dev/tty7'
display-device = ''
remote-host-name = ''
is-local = TRUE
on-since = '2015-03-30T17:46:16.216036Z'
login-session-id = '2'
Seems these updates aren't ready to be rolled out for Gnome Desktops.
I filed this bug: https://bugs.funtoo.org/browse/FL-2232
